Higher Order Correction to Screening Constant

抄録

An evaluation is carried out for corrections to screening constant and correction to the dispersion coefficient for the plasmon energy in a degenerate electron gas due to diagrams which consist of all possible combinations of “ladder interaction” and “exchange self energy” without making use of the high density approximation. Also contribution of diagrams consisting of all possible combinations of “exchange self energy” to the low temperature specific heat is computed. It is shown that the exchange effect of the effective interaction has little effect on the low temperature specific heat and that higher order diagrams in the “ladder interaction” have appreciable contribution to screening constant. It is also shown that correction factor for the dispersion coefficient of the plasmon energy is larger then unity for r_s>1 and that the convergence of high density expansion is very slow especially for the exchange effect of the effective interaction and the results obtained by using the high density approximation are found to overestimate the exchange effect.